my species wears one, and i somewhat do. Im one of those poor furries that cant buy anything on his own, so he has to make it, so i just recently made my own chain-linked collar.
Why i wear it? Well, its not because im submissive (im really submissive...even though im a silver wolf....o.o;)
Its like what Raef said long time ago, somewhat. Theres a constant leash tied onto us constantly, inwhich no one can break, and that is being Human. Since not everyone can wear fursuits out in public, i wear my collar to symbolize my furriness.
xD ok...that that i read what i typed...that makes no sense whatso ever...but you get the idea im going for..